posted by
someone claiming to be bobski
on
Thu Oct 14 05:46 CST 2004 [ RELATED]
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I drive down a 6 mile canyon daily 8%avg. grade. M47 5speed, and i use mostly brakes. My calipers,rotors,rims really hot, somtimes smell. I don't ride the brakes but slow down then let off. My pads have worn really quick, the rubber hoses are cracking and i am wondering 1. if the old hoses are not letting the pads fully release?, 2.should i be using the tranny instead of the brakes ? 3 always thought pads are cheaper than a new tranny.4. Insalling SS.hoses have ate pdisks use ate blue fluid. Give me a lesson, All info appreciated, thanks Bob.
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Downshift and use clutch gently. Find the right gear and you can "coast" down the hill without over-revving or melting/warping your brakes, saving those for occasional use at the sharp turns, stop signs, etc. Won't hurt your car provided youre not already nursing along a damaged clutch, tranny, ujoints, or differential. Ride the brakes down the hill, you can kiss your lil rotors goodbye.
--
80 262C Coupe- (FSO black, M46, original) 82 244GLT- (auto)
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Well rotors are cheap, I've just discovered, much easier than replacing a clutch. All the same, I'd rather shift down first, and have nice cold brakes to suplement it.
--
Drive it like you hate it
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I agree that the tranny, clutch and engine are more expensive than brake
pads but I disagree that using engine braking is any more harmful than using
the same engine to climb the same hill, in fact at comparable rpm the stresses
are LESS. Furthermore the reason that those components are more expensive is
not relevant either, unless you rev your engine too high. The engine will
NOT overheat with engine braking, and neither will the tranny. If you use
the clutch correctly it won't either. All of these components are made to
take the kinds of loads involved on a relatively continuous basis.
As far as the brake lines are concerned, I am not sure if the problem relates
to the newer 200 series, but the 140/164 DID have a chronic problem with tiny
rubber hoses (less than 1/8" ID) that, when used with DOT 3 or 4 brake fluids,
in conjunction with the swaged ferrules on the fittings, would swell shut.
These DID prevent brake release and wiped out a couple disks and several sets
of brake pads for me before I figured out what the problem was. The hoses
looked essentially new on the outside but just beyond the (1/8" OD) hose barb,
were swollen completely shut.
Braking pressure would force fluid through to apply the brakes but the fluid
had no pressure to force it back to release the brakes. The temporary cure
was to get new rubber lines, which would last a year or so before they too
swelled shut. The permanent cure is to get hoses made out of something
other than rubber, like the braided hoses sold by IPD and others. This is
not snake oil, it is a real problem with a real cure.
I've got lots of miles on a couple of my cars (500,000 spread between 2 of them)and when called for, and have done some pretty heavy-duty downshifting. I have
seen a LOT more engine damage attributable to flooding carburetors, mis-set
valve clearance and ignition timing than to plain old engine braking.
--
George Downs, Bartlesville, Oklahoma, Central US
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Put in the SS hoses. Get harder pads (PBR?), have rotors turned B4 pad install.
Use brakes, gears only if much more slowing needed. Apply hard, back off to cool, apply hard, back off, etc. etc.
Want 30 mph? Brake to 25, off to 35, brake to 25, etc. Experiment with what works best, depends on road, curves, etc.
What year is your brick? Does it have ventilated rotors? If not, solids can often be installed. Requires different calipers.
Are the rear brakes working well? Sometimes hard to tell.
There's always the E-brake, too. Pull up with thumb on button so at to not lock on.
Good Luck,
Bob
:>)
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"...have rotors turned B4 pad install."
Correct me if I'm wrong, but didn't Volvo put out a bulletin advising that one shouldn't use machined/turned rotors?
A new pair of Brembos from IPD isn't that much more then getting rotors turned, and a new pair of rotors will always be truer then a machined pair, as I understand it.
--
If you listen to the radio in Portland, OR, you may know me as "Portland's Favorite Soul Brother!"
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Apply hard, back off to cool, apply hard, back off, etc. etc.
I have a commercial driver's license with an air brake and passenger endorsement. In training the FIRST thing we were taught is to NOT do what you are suggesting. A light brake application over the course of several minutes will not cause problems with brake fading (i.e., overheating), but the stop and start method will absolutely ruin brakes in a very short time, and cause extremely dangerous brake fade situations at times when you need your brakes the most. The reason being that your brakes DO NOT cool off quickly between applications of the start and stop method. Applying the brakes hard heats the brakes up much more quickly than a light application, and your brakes won't cool down before the next hard application. It takes a long time for brakes to cool down, and the start and stop method is very inefficient at cooling, so it ends up accumulating much more heat in the brakes overall. The DOT has done many tests that prove this.
Passenger cars do not have engine braking systems that the big diesel rigs and buses do (i.e., "jake brakes"). So the best way to handle a downgrade in a manual transmission passenger vehicle is downshifting to third or fourth gear (if you have a tach it helps to decide what gear is best so that you're not approaching the redline), with a light application of brakes if necessary. Automatic transmission Volvos can engage the overdrive lockout if the grade is steep enough to necessitate the extra precaution, but beyond that must rely on braking alone.
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posted by
someone claiming to be B.C, away from home.
on
Thu Oct 14 15:27 CST 2004 [ RELATED]
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My points were made without your big rig training. Thank you.
I experienced rake fluid boiling on a 1984 244 DL with vented rotors and using DOT-4 fluid. Caliper got really hot, and the one front wheel would not release. That was my reason for the suggestion.
Regards,
Bob
:>)
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posted by
someone claiming to be 240snowmobile
on
Thu Oct 14 06:13 CST 2004 [ RELATED]
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Pads ARE a lot cheaper than a new engine or transmission, which you need to save for the trip back up the canyon. Describe your interpretation of "really quick". While living and driving in a hilly area (with an M47 II) it was common to replace the front pads every 6 months and the rears every 12.
The old hoses should not prevent the pads from releasing unless their insides are crudded up and so badly restricted they and block the return flow. If they are cracking they should certainly be replaced.
SS braided hoses are in my opinion not worth the investment unless you are making a show car and regularly park over a fullsize mirror or have large open rims to see through. Inside it is still reinforced rubber and becomes impossible to see if they are degrading.
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posted by
someone claiming to be 240snowmobile
on
Fri Oct 15 04:56 CST 2004 [ RELATED]
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Somehow I just knew this topic would bring out plenty of healthy (almost religious) debate :)
A related story:
I once had a women plow her Pathfinder into the back of my 240 one winter. I was stopped behind a bus, it was snowing heavily and the roads were icy. I saw her coming in my mirror and tried to get out of her way as best as I could with the limited room I had, leaned back against the seat and waited for the inevitable. I did see her frantically rowing through the gears and swerving all over the place and couldn't figure out what all the commotion was about. When we traded information in the back of a cruiser she explained how she had tried to use the gears to stop "as she had been taught" and couldn't quite avoid me. WTF?
It was a newer model so there is a good chance it had ABS. And it may or may not have had a limited slip diff in the rear, and very likely not in the front. The consequence of that is you have a similar effect braking as you do when you try to take off in a hurry; one wheel will spin and the other will roll with the car. In a braking situation one wheel will 'brake' harder than the other and most likely lock up. Anyway, the net effect is your braking is now horribly imbalanced.
I think that was a classic example of someone being taught to use the engine first, the brakes second and taking it to a new level, impulsively relying on engine braking for normal situations where the real brakes would do a much better job - as they were intended to do. If you want to slow down or stop with the best balance and control, the foot brakes are the only way.
I'm not bashing engine braking - heck, I do it in the right situations - but the foot brakes are always my first choice, not the second. Especially since the 240 4-wheel disc brake system is one of the best factory offerings around, so why not take advantage of it. (That said, I would strongly discourage anyone from using the parking brake for long descents or anything other than parking or emergencies!)
Btw, my brick survived with relatively minor injuries. The Pathfinder glanced off me and slammed into a second car in the other lane, and didn't fair nearly as well. Maybe there is some justice in life after all. (No people or animals were harmed.)
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I have NEVER heard of anyone losing either a tranny or an engine from using engine braking ..unless of course you over rev the engine .. you can also use the brakes along with the gearing down and it will be easier on all components. I have used this method since I started driving back in the stone ages with no problems on any make of car with either a manual or Automatic tranny.... at age 60 I have been on the roads since 1960 and I wouldn't want to even estimate how many miles are on my chassis :-)
Brett
PS Ever notice those signs advising truckers to "Engage Lower Gear" for long, steep descents ??
--
Brett Sutherland & the 1.5 million mile 122 CANADIAN www.ecvintagevolvo.com
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Quite. In fact, all of the British trained drivers in my family (who had to learn on manual transmissions) immediately piped up about the superior control and economy from downshifting when going downhill (I got my brick on Vancouver Island which is quite hilly). It is AFAICS an acknowledged motoring fact that this is the preferred technique, and it gives a manual driver an advantage over an automatic driver.
I also find that the M46 transmission is fairly truckish anyway, and won't object to any kind of downhill trip in 4th or 3rd. These cars might be slow, but they do their pushing and pulling rather insistently.
--
__Stef -- 81 DL wagon B21A SU carb M46 314000km
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I think the case against shifting down is that you put more wear on the engine, transmission, and clutch, all of which are valid. It isn't that you will ruin an engine by doing it once! It's about the wear over the long haul. Your age and how many miles you've put on vehicles is not relevant. People who downshift as a rule to slow a car down are putting the extra wear on the car's most expensive components, rather than on the brake pads and rotors, which are inexpensive and designed for the job.
That said, long and steep grades often do require downshifting.
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If you're already using engine braking, then you have brakes to spare. I know it's not that kind on my clutch, but I do drive hills where I feel my brakes start to fade. If I rely on downshifts into second, without too much pressure on the pads, I know I've still got cold brakes when I need them.
--
Drive it like you hate it
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posted by
someone claiming to be bobski
on
Sat Oct 16 04:57 CST 2004 [ RELATED]
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Thanks All, i will modify my technique. Bob.
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